In certain types of signal processing systems, such as parameter measurement and display systems found in motor vehicles, the system supply voltage is not regulated. When the supply voltage is not regulated the parameter senders and sensors may provide output signals that vary with the supply voltage. Electronic processing circuitry within the system for processing the sender signals may have built in regulated voltage supplies, as is required in many integrated circuit systems.
When a sender output signal varies with vehicle supply voltage, and the signal processing circuitry includes a regulated supply voltage, the output of the system may indicate that the parameter being measured is varying, when in fact it is the vehicle supply voltage that is varying. To add regulated voltage supplies for all of the vehicle senders may be an expensive method of overcoming this tendency.
What is desired is a means for parameter measurement and signal processing for systems where the supply voltage may vary and the signal processing circuitry has regulated voltage supplies. It is desirable for the system to be unaffected by supply voltage variations and is suitable for installation into different types of systems.